Costs and effects of on-demand treatment of hereditary angioedema in Italy: a prospective cohort study of 167 patients

OBJECTIVES: To explore treatment behaviours in a cohort of Italian patients with hereditary angioedema due to complement C1-inhibitor deficiency (C1-INH-HAE), and to estimate how effects and costs of treating attacks in routine practice differed across available on-demand treatments. DESIGN: Cost analyses and survival analyses using attack-level data collected prospectively for 1 year. SETTING: National reference centre for C1-INH-HAE. PARTICIPANTS: 167 patients with proved diagnosis of C1-INH-HAE, who reported data on angioedema attacks, including severity, localisation and duration, treatment received, and use of other healthcare services. INTERVENTIONS: Attacks were treated with either icatibant, plasma-derived C1-INH (pdC1-INH) or just supportive care. MAIN OUTCOME MEASURES: Treatment efficacy in reducing attack duration and the direct costs of acute attacks. RESULTS: Overall, 133 of 167 patients (79.6%) reported 1508 attacks during the study period, with mean incidence of 11 attacks per patient per year. Only 78.9% of attacks were treated in contrast to current guidelines. Both icatibant and pdC1-INH significantly reduced attack duration compared with no treatment (median times from onset 7, 10 and 47 hours, respectively), but remission rates with icatibant were 31% faster compared with pdC1-INH (HR 1.31, 95% CI 1.14 to 1.51). However, observed treatment behaviours suggest patterns of suboptimal dosing for pdC1-INH. The average cost per attack was €1183 (SD €789) resulting in €1.58 million healthcare costs during the observation period (€11 912 per patient per year). Icatibant was 54% more expensive than pdC1-INH, whereas age, sex and prophylactic treatment were not associated to higher or lower costs. CONCLUSIONS: Both icatibant and pdC1-INH significantly reduced attack duration compared with no treatment, however, icatibant was more effective but also more expensive. Treatment behaviours and suboptimal dosing of pdC1-INH may account for the differences, but further research is needed to define their role.